Yes it is debateable as I can't remember now (VrsAlex?) recently took a head apart that had had a catchcan fitted and the valves were completely covered in carbon as if it had never had one on.
I personally can't see the difference between a catchcan and the pcv revamp or even PCV as the oil and gunk just drains back into the engine.
Does the PCV not just use the vacuum from the engine intake to pull more out?
I am lead to believe that the only effective method of stopping the head and valves carbonising is WMI.
Nail on theee head!
A catch can will NOT stop the inlet valves getting sh*tty at all, although it will reduce it
By their very nature the only thing to stop DFI'S gunking up is WMI, nitrous or extra injectors in the inlet manifold say on a BT car
My demo cars inlet valves are like new (direct port WMI)
All the new DFI Porsches are the same! all gunky in the inlet chambers, other manufactures cars too
I use the BSH PCV blank on the Loba car but it's not ideal, it's ok for reliability reasons but the concern for me is blow back